xref: /openbmc/linux/net/ipv4/fib_rules.c (revision 3d3337de)
1 /*
2  * INET		An implementation of the TCP/IP protocol suite for the LINUX
3  *		operating system.  INET is implemented using the  BSD Socket
4  *		interface as the means of communication with the user level.
5  *
6  *		IPv4 Forwarding Information Base: policy rules.
7  *
8  * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
9  *		Thomas Graf <tgraf@suug.ch>
10  *
11  *		This program is free software; you can redistribute it and/or
12  *		modify it under the terms of the GNU General Public License
13  *		as published by the Free Software Foundation; either version
14  *		2 of the License, or (at your option) any later version.
15  *
16  * Fixes:
17  *		Rani Assaf	:	local_rule cannot be deleted
18  *		Marc Boucher	:	routing by fwmark
19  */
20 
21 #include <linux/types.h>
22 #include <linux/kernel.h>
23 #include <linux/netdevice.h>
24 #include <linux/netlink.h>
25 #include <linux/inetdevice.h>
26 #include <linux/init.h>
27 #include <linux/list.h>
28 #include <linux/rcupdate.h>
29 #include <linux/export.h>
30 #include <net/ip.h>
31 #include <net/route.h>
32 #include <net/tcp.h>
33 #include <net/ip_fib.h>
34 #include <net/fib_rules.h>
35 
36 struct fib4_rule {
37 	struct fib_rule		common;
38 	u8			dst_len;
39 	u8			src_len;
40 	u8			tos;
41 	__be32			src;
42 	__be32			srcmask;
43 	__be32			dst;
44 	__be32			dstmask;
45 #ifdef CONFIG_IP_ROUTE_CLASSID
46 	u32			tclassid;
47 #endif
48 };
49 
50 int __fib_lookup(struct net *net, struct flowi4 *flp, struct fib_result *res)
51 {
52 	struct fib_lookup_arg arg = {
53 		.result = res,
54 		.flags = FIB_LOOKUP_NOREF,
55 	};
56 	int err;
57 
58 	err = fib_rules_lookup(net->ipv4.rules_ops, flowi4_to_flowi(flp), 0, &arg);
59 #ifdef CONFIG_IP_ROUTE_CLASSID
60 	if (arg.rule)
61 		res->tclassid = ((struct fib4_rule *)arg.rule)->tclassid;
62 	else
63 		res->tclassid = 0;
64 #endif
65 
66 	if (err == -ESRCH)
67 		err = -ENETUNREACH;
68 
69 	return err;
70 }
71 EXPORT_SYMBOL_GPL(__fib_lookup);
72 
73 static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp,
74 			    int flags, struct fib_lookup_arg *arg)
75 {
76 	int err = -EAGAIN;
77 	struct fib_table *tbl;
78 
79 	switch (rule->action) {
80 	case FR_ACT_TO_TBL:
81 		break;
82 
83 	case FR_ACT_UNREACHABLE:
84 		return -ENETUNREACH;
85 
86 	case FR_ACT_PROHIBIT:
87 		return -EACCES;
88 
89 	case FR_ACT_BLACKHOLE:
90 	default:
91 		return -EINVAL;
92 	}
93 
94 	rcu_read_lock();
95 
96 	tbl = fib_get_table(rule->fr_net, rule->table);
97 	if (tbl)
98 		err = fib_table_lookup(tbl, &flp->u.ip4,
99 				       (struct fib_result *)arg->result,
100 				       arg->flags);
101 
102 	rcu_read_unlock();
103 	return err;
104 }
105 
106 static bool fib4_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
107 {
108 	struct fib_result *result = (struct fib_result *) arg->result;
109 	struct net_device *dev = NULL;
110 
111 	if (result->fi)
112 		dev = result->fi->fib_dev;
113 
114 	/* do not accept result if the route does
115 	 * not meet the required prefix length
116 	 */
117 	if (result->prefixlen <= rule->suppress_prefixlen)
118 		goto suppress_route;
119 
120 	/* do not accept result if the route uses a device
121 	 * belonging to a forbidden interface group
122 	 */
123 	if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
124 		goto suppress_route;
125 
126 	return false;
127 
128 suppress_route:
129 	if (!(arg->flags & FIB_LOOKUP_NOREF))
130 		fib_info_put(result->fi);
131 	return true;
132 }
133 
134 static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
135 {
136 	struct fib4_rule *r = (struct fib4_rule *) rule;
137 	struct flowi4 *fl4 = &fl->u.ip4;
138 	__be32 daddr = fl4->daddr;
139 	__be32 saddr = fl4->saddr;
140 
141 	if (((saddr ^ r->src) & r->srcmask) ||
142 	    ((daddr ^ r->dst) & r->dstmask))
143 		return 0;
144 
145 	if (r->tos && (r->tos != fl4->flowi4_tos))
146 		return 0;
147 
148 	return 1;
149 }
150 
151 static struct fib_table *fib_empty_table(struct net *net)
152 {
153 	u32 id;
154 
155 	for (id = 1; id <= RT_TABLE_MAX; id++)
156 		if (!fib_get_table(net, id))
157 			return fib_new_table(net, id);
158 	return NULL;
159 }
160 
161 static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {
162 	FRA_GENERIC_POLICY,
163 	[FRA_FLOW]	= { .type = NLA_U32 },
164 };
165 
166 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
167 			       struct fib_rule_hdr *frh,
168 			       struct nlattr **tb)
169 {
170 	struct net *net = sock_net(skb->sk);
171 	int err = -EINVAL;
172 	struct fib4_rule *rule4 = (struct fib4_rule *) rule;
173 
174 	if (frh->tos & ~IPTOS_TOS_MASK)
175 		goto errout;
176 
177 	/* split local/main if they are not already split */
178 	err = fib_unmerge(net);
179 	if (err)
180 		goto errout;
181 
182 	if (rule->table == RT_TABLE_UNSPEC) {
183 		if (rule->action == FR_ACT_TO_TBL) {
184 			struct fib_table *table;
185 
186 			table = fib_empty_table(net);
187 			if (!table) {
188 				err = -ENOBUFS;
189 				goto errout;
190 			}
191 
192 			rule->table = table->tb_id;
193 		}
194 	}
195 
196 	if (frh->src_len)
197 		rule4->src = nla_get_in_addr(tb[FRA_SRC]);
198 
199 	if (frh->dst_len)
200 		rule4->dst = nla_get_in_addr(tb[FRA_DST]);
201 
202 #ifdef CONFIG_IP_ROUTE_CLASSID
203 	if (tb[FRA_FLOW]) {
204 		rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
205 		if (rule4->tclassid)
206 			net->ipv4.fib_num_tclassid_users++;
207 	}
208 #endif
209 
210 	rule4->src_len = frh->src_len;
211 	rule4->srcmask = inet_make_mask(rule4->src_len);
212 	rule4->dst_len = frh->dst_len;
213 	rule4->dstmask = inet_make_mask(rule4->dst_len);
214 	rule4->tos = frh->tos;
215 
216 	net->ipv4.fib_has_custom_rules = true;
217 	fib_flush_external(rule->fr_net);
218 
219 	err = 0;
220 errout:
221 	return err;
222 }
223 
224 static int fib4_rule_delete(struct fib_rule *rule)
225 {
226 	struct net *net = rule->fr_net;
227 	int err;
228 
229 	/* split local/main if they are not already split */
230 	err = fib_unmerge(net);
231 	if (err)
232 		goto errout;
233 
234 #ifdef CONFIG_IP_ROUTE_CLASSID
235 	if (((struct fib4_rule *)rule)->tclassid)
236 		net->ipv4.fib_num_tclassid_users--;
237 #endif
238 	net->ipv4.fib_has_custom_rules = true;
239 	fib_flush_external(rule->fr_net);
240 errout:
241 	return err;
242 }
243 
244 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
245 			     struct nlattr **tb)
246 {
247 	struct fib4_rule *rule4 = (struct fib4_rule *) rule;
248 
249 	if (frh->src_len && (rule4->src_len != frh->src_len))
250 		return 0;
251 
252 	if (frh->dst_len && (rule4->dst_len != frh->dst_len))
253 		return 0;
254 
255 	if (frh->tos && (rule4->tos != frh->tos))
256 		return 0;
257 
258 #ifdef CONFIG_IP_ROUTE_CLASSID
259 	if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
260 		return 0;
261 #endif
262 
263 	if (frh->src_len && (rule4->src != nla_get_in_addr(tb[FRA_SRC])))
264 		return 0;
265 
266 	if (frh->dst_len && (rule4->dst != nla_get_in_addr(tb[FRA_DST])))
267 		return 0;
268 
269 	return 1;
270 }
271 
272 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
273 			  struct fib_rule_hdr *frh)
274 {
275 	struct fib4_rule *rule4 = (struct fib4_rule *) rule;
276 
277 	frh->dst_len = rule4->dst_len;
278 	frh->src_len = rule4->src_len;
279 	frh->tos = rule4->tos;
280 
281 	if ((rule4->dst_len &&
282 	     nla_put_in_addr(skb, FRA_DST, rule4->dst)) ||
283 	    (rule4->src_len &&
284 	     nla_put_in_addr(skb, FRA_SRC, rule4->src)))
285 		goto nla_put_failure;
286 #ifdef CONFIG_IP_ROUTE_CLASSID
287 	if (rule4->tclassid &&
288 	    nla_put_u32(skb, FRA_FLOW, rule4->tclassid))
289 		goto nla_put_failure;
290 #endif
291 	return 0;
292 
293 nla_put_failure:
294 	return -ENOBUFS;
295 }
296 
297 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
298 {
299 	return nla_total_size(4) /* dst */
300 	       + nla_total_size(4) /* src */
301 	       + nla_total_size(4); /* flow */
302 }
303 
304 static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
305 {
306 	rt_cache_flush(ops->fro_net);
307 }
308 
309 static const struct fib_rules_ops __net_initconst fib4_rules_ops_template = {
310 	.family		= AF_INET,
311 	.rule_size	= sizeof(struct fib4_rule),
312 	.addr_size	= sizeof(u32),
313 	.action		= fib4_rule_action,
314 	.suppress	= fib4_rule_suppress,
315 	.match		= fib4_rule_match,
316 	.configure	= fib4_rule_configure,
317 	.delete		= fib4_rule_delete,
318 	.compare	= fib4_rule_compare,
319 	.fill		= fib4_rule_fill,
320 	.default_pref	= fib_default_rule_pref,
321 	.nlmsg_payload	= fib4_rule_nlmsg_payload,
322 	.flush_cache	= fib4_rule_flush_cache,
323 	.nlgroup	= RTNLGRP_IPV4_RULE,
324 	.policy		= fib4_rule_policy,
325 	.owner		= THIS_MODULE,
326 };
327 
328 static int fib_default_rules_init(struct fib_rules_ops *ops)
329 {
330 	int err;
331 
332 	err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0);
333 	if (err < 0)
334 		return err;
335 	err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0);
336 	if (err < 0)
337 		return err;
338 	err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0);
339 	if (err < 0)
340 		return err;
341 	return 0;
342 }
343 
344 int __net_init fib4_rules_init(struct net *net)
345 {
346 	int err;
347 	struct fib_rules_ops *ops;
348 
349 	ops = fib_rules_register(&fib4_rules_ops_template, net);
350 	if (IS_ERR(ops))
351 		return PTR_ERR(ops);
352 
353 	err = fib_default_rules_init(ops);
354 	if (err < 0)
355 		goto fail;
356 	net->ipv4.rules_ops = ops;
357 	net->ipv4.fib_has_custom_rules = false;
358 	return 0;
359 
360 fail:
361 	/* also cleans all rules already added */
362 	fib_rules_unregister(ops);
363 	return err;
364 }
365 
366 void __net_exit fib4_rules_exit(struct net *net)
367 {
368 	fib_rules_unregister(net->ipv4.rules_ops);
369 }
370